Losses of honey bee colonies over the 2012/13 winter - Preliminary results from an international study

The honey bee research network COLOSS 1 has today announced the preliminary results of an internationalstudy to investigate winter colony losses. Data were collected from 19 countries from Europe, Israel andAlgeria. In total, more than 15,000 beekeepers provided overwintering mortality and other data of theircolonies. Collectively, they managed more than 280,000 colonies. A preliminary analysis of the data showsthat the mortality rate over the 2012-13 winter varied between countries, ranging from 6% in Israel to 37%in Ireland, and there were also marked regional differences within some countries. These figures comparewith losses over the same period of 31% and 34% recently reported from the USA 2 and the UK 3 respectively.

The protocol used to collect this COLOSS data has been internationally standardized to allow comparisons and jointanalysis of the data. A more detailed analysis of risk factors calculated from the whole dataset , as well as furthercolony loss data from other countries will be published in the peer-reviewed Journal of Apicultural Research 4 later inthe year. The data show that Poland and Finland have each year experienced losses of about 17%. Countries in southeastern Europe (Slovakia, Bosnia Herzegovina, Croatia) have had average losses of less than 10%, but in 2012 losseswere slightly higher. In central Europe (Germany, Switzerland, Austria) losses rose to above 20% in 2012 but went backto around 15% in 2013. In the neighbouring Netherlands, losses were above 20% for five years, but decreased in 2013to a level comparable with Germany and Switzerland. Interestingly, we now see losses rising to substantially higherlevels in northern countries (Sweden, Denmark, Norway, Ireland, UK) whose losses were around the 15% in theprevious years.

Co-ordinator of the COLOSS Monitoring and Diagnosis Working Group Dr Romée van der Zee from the Dutch Centrefor Bee Research says: “We have observed an interesting pattern in honey bee colony losses over the last 3 years. Theseresults emphasise that losses in many countries remain greater than beekeepers consider are acceptable. We believethat many factors including the weather are responsible for these losses, which show patterns over the years which arenot bound to administrative borders”. [Ends]